ComputerForensicsDigest.com

Last April, a murder in Boston's tony Back Bay made headlines across the country. From one perspective, there was sadly nothing remarkable about the crime: a woman advertising erotic services ("massage") was assaulted and murdered by a customer. But what caught everyone's attention was the fact that the alleged killer found his victim on Craigslist, an online classified advertising site that included a category called "Erotic Services."

In a lengthy and detailed article in this month's Vanity Fair, writer Maureen Orth describes the events leading up to the death of 25-year-old Julissa Brisman and the investigation that led to the arrest of Philip Markoff.

While not very technical, the article is an excellent overview of the growing connections between several different types of digital forensics: computer, mobile, and cloud. Some of the first clues, for instance, were obtained when Brisman's boss (who was actually located on the West Coast) turned over access to her service's Yahoo message account, as well as the email name and address of the person Brisman was scheduled to meet.

Armed with the email address, police officers were able to obtain warrants to find out the name of the person using the account. They were also able to obtain detailed information from Craigslist about when various online ads were accessed and from what locations. The email account was a recent creation, but the Internet Service Provider was still able to provide police with a physical address associated with the IP address.

The trail might have ended there. Since the physical address was a large apartment building and the IP address was an unsecured router, the number of potential users was quite large. But police had non-digital evidence to assist the manhunt: photos of a potential suspect taken from hotel surveillance cameras and identified by one of the attacker's other victims. After a relatively short stakeout of the apartment building, officers saw a man matching their description leaving the building. It was Philip Markoff.

Prosecutors indicted Markoff on charges of first-degree murder, kidnapping and armed robbery, and trial is tentatively set for June 1, 2010.

Despite its cooperation with law enforcement during the investigation, Craigslist came under widespread criticism for its "Erotic Services" category, which some argued was little more than an electronic catalog of prostitution. After some initial resistance, Craigslist agreed to make changes in its service, and replaced the Erotic Services listings with a new category called "Adult Services," in which each ad is manually screened to make sure that it is not a front for illegal services.

While it may be true that newer "Adult Services" ads are more discreet in terms of what they offer, it's not hard to imagine that some age-old transactions are occurring when the hotel door is shut. Sadly, it's also not hard to imagine that this will not be the last time that investigators follow an electronic trail that begins at Craigslist and wends it way through the cloud.